510 Barbour— Carboniferous Euryjpterids of Nebraska. 



the second and third somites, and tapers gradually to the tel- 

 son. In none of the somites are the pleura produced into 

 sharp angles or spines as far as can be observed. The eyes are 

 roundish-reniform, and are set far apart, close to the cephalic 

 rim. Ocelli are not discoverable. The front of the cephalon 

 is ornamented by fine, closely crowded, vermicular lines, which 

 curve forward and outward from the median line until they 

 meet the cephalic rim. 



Measurements: The cephalothorax is 9'5 mm long by ll mm 

 wide at its base. The preabdomen is 9 mm long by 12 mm wide 

 at segment 3, its widest point. Segment No. 7 is *5 mm long by 

 ll 1 ™ wide. No. 8 is l'5 mm long by 12 mm wide. 



Each of the others approximate l'75 mm . In the postabdo- 

 men segment No. 13 measures 2*5 mm long by 8 mm wide. No. 18 

 is 5 mm long by 3 mm wide. See fig. 1 ; § nat. size. 



Eurypterus, sp. 



This form, possibly a different species, has a noticeably 

 inflated body ; long narrow paddles ; and pleura seemingly 

 produced into spines. See fig. 2. 



Segments 11, 12, 13 are short, possibly because telescoped. 

 This may account also for the expanded body. At any rate 

 this specimen was the only one of the kind found. It is 

 pressed as flat as tissue paper, and it seems to be the ventral 

 surface which is exposed. 



The elliptical portion of the head, which is unmistakably 

 defined, is taken to be the metastoma, and yet it is altogether 

 too large. It extends well across the head-shield. The median 

 opercular process, assuming it to be such, is broad and well 

 defined proximally, and is fairly distinct along one border. 

 Segment 1, coxa, of the paddles seems plain, while 2 and 3 

 are reasonably so. 



The specimen is small and colored like its background. 

 Accordingly blemishes and irregularities are not always dis- 

 tinguishable from articulations. The greatest width of the 

 preabdomen is between segments 10 and 11. The head -shield 

 is Y mm long by 8 mra wide. Figures 1 and 2 (f nat. size) were 

 obtained by tracing around enlarged photographs, and are 

 thought to be reasonably accurate. 



Lincoln, Nebraska, July 15, 1914. 



